1PCRE2GREP(1) General Commands Manual PCRE2GREP(1)
2
6 pcre2grep - a grep with Perl-compatible regular expressions.
7
9 pcre2grep [options] [long options] [pattern] [path1 path2 ...]
10
12 pcre2grep searches files for character patterns, in the same way as
14 other grep commands do, but it uses the PCRE2 regular expression li‐
15 brary to support patterns that are compatible with the regular expres‐
16 sions of Perl 5. See pcre2syntax(3) for a quick-reference summary of
17 pattern syntax, or pcre2pattern(3) for a full description of the syntax
18 and semantics of the regular expressions that PCRE2 supports.
19 Patterns, whether supplied on the command line or in a separate file,
21 are given without delimiters. For example:
22 pcre2grep Thursday /etc/motd
24 If you attempt to use delimiters (for example, by surrounding a pattern
26 with slashes, as is common in Perl scripts), they are interpreted as
27 part of the pattern. Quotes can of course be used to delimit patterns
28 on the command line because they are interpreted by the shell, and in‐
29 deed quotes are required if a pattern contains white space or shell
30 metacharacters.
31 The first argument that follows any option settings is treated as the
33 single pattern to be matched when neither -e nor -f is present. Con‐
34 versely, when one or both of these options are used to specify pat‐
35 terns, all arguments are treated as path names. At least one of -e, -f,
36 or an argument pattern must be provided.
37 If no files are specified, pcre2grep reads the standard input. The
39 standard input can also be referenced by a name consisting of a single
40 hyphen. For example:
41 pcre2grep some-pattern file1 - file3
43 By default, input files are searched line by line. Each line that
45 matches a pattern is copied to the standard output, and if there is
46 more than one file, the file name is output at the start of each line,
47 followed by a colon. However, there are options that can change how
48 pcre2grep behaves. For example, the -M option makes it possible to
49 search for strings that span line boundaries. What defines a line
50 boundary is controlled by the -N (--newline) option. The -h and -H op‐
51 tions control whether or not file names are shown, and the -Z option
52 changes the file name terminator to a zero byte.
53 The amount of memory used for buffering files that are being scanned is
55 controlled by parameters that can be set by the --buffer-size and
56 --max-buffer-size options. The first of these sets the size of buffer
57 that is obtained at the start of processing. If an input file contains
58 very long lines, a larger buffer may be needed; this is handled by au‐
59 tomatically extending the buffer, up to the limit specified by --max-
60 buffer-size. The default values for these parameters can be set when
61 pcre2grep is built; if nothing is specified, the defaults are set to
62 20KiB and 1MiB respectively. An error occurs if a line is too long and
63 the buffer can no longer be expanded.
64 The block of memory that is actually used is three times the "buffer
66 size", to allow for buffering "before" and "after" lines. If the buffer
67 size is too small, fewer than requested "before" and "after" lines may
68 be output.
69 Patterns can be no longer than 8KiB or BUFSIZ bytes, whichever is the
71 greater. BUFSIZ is defined in <stdio.h>. When there is more than one
72 pattern (specified by the use of -e and/or -f), each pattern is applied
73 to each line in the order in which they are defined, except that all
74 the -e patterns are tried before the -f patterns.
75 By default, as soon as one pattern matches a line, no further patterns
77 are considered. However, if --colour (or --color) is used to colour the
78 matching substrings, or if --only-matching, --file-offsets, --line-off‐
79 sets, or --output is used to output only the part of the line that
80 matched (either shown literally, or as an offset), the behaviour is
81 different. In this situation, all the patterns are applied to the line.
82 If there is more than one match, the one that begins nearest to the
83 start of the subject is processed; if there is more than one match at
84 that position, the one with the longest matching substring is pro‐
85 cessed; if the matching substrings are equal, the first match found is
86 processed.
87 Scanning with all the patterns resumes immediately following the match,
89 so that later matches on the same line can be found. Note, however,
90 that an overlapping match that starts in the middle of another match
91 will not be processed.
92 The above behaviour was changed at release 10.41 to be more compatible
94 with GNU grep. In earlier releases, pcre2grep did not recognize matches
95 from later patterns that were earlier in the subject.
96 Patterns that can match an empty string are accepted, but empty string
98 matches are never recognized. An example is the pattern "(su‐
99 per)?(man)?", in which all components are optional. This pattern finds
100 all occurrences of both "super" and "man"; the output differs from
101 matching with "super|man" when only the matching substrings are being
102 shown.
103 If the LC_ALL or LC_CTYPE environment variable is set, pcre2grep uses
105 the value to set a locale when calling the PCRE2 library. The --locale
106 option can be used to override this.
107
109 Compile-time options for pcre2grep can set it up to use libz or libbz2
111 for reading compressed files whose names end in .gz or .bz2, respec‐
112 tively. You can find out whether your pcre2grep binary has support for
113 one or both of these file types by running it with the --help option.
114 If the appropriate support is not present, all files are treated as
115 plain text. The standard input is always so treated. If a file with a
116 .gz or .bz2 extension is not in fact compressed, it is read as a plain
117 text file. When input is from a compressed .gz or .bz2 file, the
118 --line-buffered option is ignored.
119
121 By default, a file that contains a binary zero byte within the first
123 1024 bytes is identified as a binary file, and is processed specially.
124 However, if the newline type is specified as NUL, that is, the line
125 terminator is a binary zero, the test for a binary file is not applied.
126 See the --binary-files option for a means of changing the way binary
127 files are handled.
128
130 Patterns passed from the command line are strings that are terminated
132 by a binary zero, so cannot contain internal zeros. However, patterns
133 that are read from a file via the -f option may contain binary zeros.
134
136 The order in which some of the options appear can affect the output.
138 For example, both the -H and -l options affect the printing of file
139 names. Whichever comes later in the command line will be the one that
140 takes effect. Similarly, except where noted below, if an option is
141 given twice, the later setting is used. Numerical values for options
142 may be followed by K or M, to signify multiplication by 1024 or
143 1024*1024 respectively.
144 -- This terminates the list of options. It is useful if the next
146 item on the command line starts with a hyphen but is not an
147 option. This allows for the processing of patterns and file
148 names that start with hyphens.
149 -A number, --after-context=number
151 Output up to number lines of context after each matching
152 line. Fewer lines are output if the next match or the end of
153 the file is reached, or if the processing buffer size has
154 been set too small. If file names and/or line numbers are be‐
155 ing output, a hyphen separator is used instead of a colon for
156 the context lines (the -Z option can be used to change the
157 file name terminator to a zero byte). A line containing "--"
158 is output between each group of lines, unless they are in
159 fact contiguous in the input file. The value of number is ex‐
160 pected to be relatively small. When -c is used, -A is ig‐
161 nored.
162 -a, --text
164 Treat binary files as text. This is equivalent to --binary-
165 files=text.
166 --allow-lookaround-bsk
168 PCRE2 now forbids the use of \K in lookarounds by default, in
169 line with Perl. This option causes pcre2grep to set the
170 PCRE2_EXTRA_ALLOW_LOOKAROUND_BSK option, which enables this
171 somewhat dangerous usage.
172 -B number, --before-context=number
174 Output up to number lines of context before each matching
175 line. Fewer lines are output if the previous match or the
176 start of the file is within number lines, or if the process‐
177 ing buffer size has been set too small. If file names and/or
178 line numbers are being output, a hyphen separator is used in‐
179 stead of a colon for the context lines (the -Z option can be
180 used to change the file name terminator to a zero byte). A
181 line containing "--" is output between each group of lines,
182 unless they are in fact contiguous in the input file. The
183 value of number is expected to be relatively small. When -c
184 is used, -B is ignored.
185 --binary-files=word
187 Specify how binary files are to be processed. If the word is
188 "binary" (the default), pattern matching is performed on bi‐
189 nary files, but the only output is "Binary file <name>
190 matches" when a match succeeds. If the word is "text", which
191 is equivalent to the -a or --text option, binary files are
192 processed in the same way as any other file. In this case,
193 when a match succeeds, the output may be binary garbage,
194 which can have nasty effects if sent to a terminal. If the
195 word is "without-match", which is equivalent to the -I op‐
196 tion, binary files are not processed at all; they are assumed
197 not to be of interest and are skipped without causing any
198 output or affecting the return code.
199 --buffer-size=number
201 Set the parameter that controls how much memory is obtained
202 at the start of processing for buffering files that are being
203 scanned. See also --max-buffer-size below.
204 -C number, --context=number
206 Output number lines of context both before and after each
207 matching line. This is equivalent to setting both -A and -B
208 to the same value.
209 -c, --count
211 Do not output lines from the files that are being scanned;
212 instead output the number of lines that would have been
213 shown, either because they matched, or, if -v is set, because
214 they failed to match. By default, this count is exactly the
215 same as the number of lines that would have been output, but
216 if the -M (multiline) option is used (without -v), there may
217 be more suppressed lines than the count (that is, the number
218 of matches).
219 If no lines are selected, the number zero is output. If sev‐
221 eral files are are being scanned, a count is output for each
222 of them and the -t option can be used to cause a total to be
223 output at the end. However, if the --files-with-matches op‐
224 tion is also used, only those files whose counts are greater
225 than zero are listed. When -c is used, the -A, -B, and -C op‐
226 tions are ignored.
227 --colour, --color
229 If this option is given without any data, it is equivalent to
230 "--colour=auto". If data is required, it must be given in
231 the same shell item, separated by an equals sign.
232 --colour=value, --color=value
234 This option specifies under what circumstances the parts of a
235 line that matched a pattern should be coloured in the output.
236 It is ignored if --file-offsets, --line-offsets, or --output
237 is set. By default, output is not coloured. The value for the
238 --colour option (which is optional, see above) may be
239 "never", "always", or "auto". In the latter case, colouring
240 happens only if the standard output is connected to a termi‐
241 nal. More resources are used when colouring is enabled, be‐
242 cause pcre2grep has to search for all possible matches in a
243 line, not just one, in order to colour them all.
244 The colour that is used can be specified by setting one of
246 the environment variables PCRE2GREP_COLOUR, PCRE2GREP_COLOR,
247 PCREGREP_COLOUR, or PCREGREP_COLOR, which are checked in that
248 order. If none of these are set, pcre2grep looks for
249 GREP_COLORS or GREP_COLOR (in that order). The value of the
250 variable should be a string of two numbers, separated by a
251 semicolon, except in the case of GREP_COLORS, which must
252 start with "ms=" or "mt=" followed by two semicolon-separated
253 colours, terminated by the end of the string or by a colon.
254 If GREP_COLORS does not start with "ms=" or "mt=" it is ig‐
255 nored, and GREP_COLOR is checked.
256 If the string obtained from one of the above variables con‐
258 tains any characters other than semicolon or digits, the set‐
259 ting is ignored and the default colour is used. The string is
260 copied directly into the control string for setting colour on
261 a terminal, so it is your responsibility to ensure that the
262 values make sense. If no relevant environment variable is
263 set, the default is "1;31", which gives red.
264 -D action, --devices=action
266 If an input path is not a regular file or a directory, "ac‐
267 tion" specifies how it is to be processed. Valid values are
268 "read" (the default) or "skip" (silently skip the path).
269 -d action, --directories=action
271 If an input path is a directory, "action" specifies how it is
272 to be processed. Valid values are "read" (the default in
273 non-Windows environments, for compatibility with GNU grep),
274 "recurse" (equivalent to the -r option), or "skip" (silently
275 skip the path, the default in Windows environments). In the
276 "read" case, directories are read as if they were ordinary
277 files. In some operating systems the effect of reading a di‐
278 rectory like this is an immediate end-of-file; in others it
279 may provoke an error.
280 --depth-limit=number
282 See --match-limit below.
283 -e pattern, --regex=pattern, --regexp=pattern
285 Specify a pattern to be matched. This option can be used mul‐
286 tiple times in order to specify several patterns. It can also
287 be used as a way of specifying a single pattern that starts
288 with a hyphen. When -e is used, no argument pattern is taken
289 from the command line; all arguments are treated as file
290 names. There is no limit to the number of patterns. They are
291 applied to each line in the order in which they are defined.
292 If -f is used with -e, the command line patterns are matched
294 first, followed by the patterns from the file(s), independent
295 of the order in which these options are specified.
296 --exclude=pattern
298 Files (but not directories) whose names match the pattern are
299 skipped without being processed. This applies to all files,
300 whether listed on the command line, obtained from --file-
301 list, or by scanning a directory. The pattern is a PCRE2 reg‐
302 ular expression, and is matched against the final component
303 of the file name, not the entire path. The -F, -w, and -x op‐
304 tions do not apply to this pattern. The option may be given
305 any number of times in order to specify multiple patterns. If
306 a file name matches both an --include and an --exclude pat‐
307 tern, it is excluded. There is no short form for this option.
308 --exclude-from=filename
310 Treat each non-empty line of the file as the data for an
311 --exclude option. What constitutes a newline when reading the
312 file is the operating system's default. The --newline option
313 has no effect on this option. This option may be given more
314 than once in order to specify a number of files to read.
315 --exclude-dir=pattern
317 Directories whose names match the pattern are skipped without
318 being processed, whatever the setting of the --recursive op‐
319 tion. This applies to all directories, whether listed on the
320 command line, obtained from --file-list, or by scanning a
321 parent directory. The pattern is a PCRE2 regular expression,
322 and is matched against the final component of the directory
323 name, not the entire path. The -F, -w, and -x options do not
324 apply to this pattern. The option may be given any number of
325 times in order to specify more than one pattern. If a direc‐
326 tory matches both --include-dir and --exclude-dir, it is ex‐
327 cluded. There is no short form for this option.
328 -F, --fixed-strings
330 Interpret each data-matching pattern as a list of fixed
331 strings, separated by newlines, instead of as a regular ex‐
332 pression. What constitutes a newline for this purpose is con‐
333 trolled by the --newline option. The -w (match as a word) and
334 -x (match whole line) options can be used with -F. They ap‐
335 ply to each of the fixed strings. A line is selected if any
336 of the fixed strings are found in it (subject to -w or -x, if
337 present). This option applies only to the patterns that are
338 matched against the contents of files; it does not apply to
339 patterns specified by any of the --include or --exclude op‐
340 tions.
341 -f filename, --file=filename
343 Read patterns from the file, one per line. As is the case
344 with patterns on the command line, no delimiters should be
345 used. What constitutes a newline when reading the file is the
346 operating system's default interpretation of \n. The --new‐
347 line option has no effect on this option. Trailing white
348 space is removed from each line, and blank lines are ignored.
349 An empty file contains no patterns and therefore matches
350 nothing. Patterns read from a file in this way may contain
351 binary zeros, which are treated as ordinary data characters.
352 If this option is given more than once, all the specified
354 files are read. A data line is output if any of the patterns
355 match it. A file name can be given as "-" to refer to the
356 standard input. When -f is used, patterns specified on the
357 command line using -e may also be present; they are matched
358 before the file's patterns. However, no pattern is taken from
359 the command line; all arguments are treated as the names of
360 paths to be searched.
361 --file-list=filename
363 Read a list of files and/or directories that are to be
364 scanned from the given file, one per line. What constitutes a
365 newline when reading the file is the operating system's de‐
366 fault. Trailing white space is removed from each line, and
367 blank lines are ignored. These paths are processed before any
368 that are listed on the command line. The file name can be
369 given as "-" to refer to the standard input. If --file and
370 --file-list are both specified as "-", patterns are read
371 first. This is useful only when the standard input is a ter‐
372 minal, from which further lines (the list of files) can be
373 read after an end-of-file indication. If this option is given
374 more than once, all the specified files are read.
375 --file-offsets
377 Instead of showing lines or parts of lines that match, show
378 each match as an offset from the start of the file and a
379 length, separated by a comma. In this mode, --colour has no
380 effect, and no context is shown. That is, the -A, -B, and -C
381 options are ignored. If there is more than one match in a
382 line, each of them is shown separately. This option is mutu‐
383 ally exclusive with --output, --line-offsets, and --only-
384 matching.
385 -H, --with-filename
387 Force the inclusion of the file name at the start of output
388 lines when searching a single file. The file name is not nor‐
389 mally shown in this case. By default, for matching lines,
390 the file name is followed by a colon; for context lines, a
391 hyphen separator is used. The -Z option can be used to change
392 the terminator to a zero byte. If a line number is also being
393 output, it follows the file name. When the -M option causes a
394 pattern to match more than one line, only the first is pre‐
395 ceded by the file name. This option overrides any previous
396 -h, -l, or -L options.
397 -h, --no-filename
399 Suppress the output file names when searching multiple files.
400 File names are normally shown when multiple files are
401 searched. By default, for matching lines, the file name is
402 followed by a colon; for context lines, a hyphen separator is
403 used. The -Z option can be used to change the terminator to a
404 zero byte. If a line number is also being output, it follows
405 the file name. This option overrides any previous -H, -L, or
406 -l options.
407 --heap-limit=number
409 See --match-limit below.
410 --help Output a help message, giving brief details of the command
412 options and file type support, and then exit. Anything else
413 on the command line is ignored.
414 -I Ignore binary files. This is equivalent to --binary-
416 files=without-match.
417 -i, --ignore-case
419 Ignore upper/lower case distinctions during comparisons.
420 --include=pattern
422 If any --include patterns are specified, the only files that
423 are processed are those whose names match one of the patterns
424 and do not match an --exclude pattern. This option does not
425 affect directories, but it applies to all files, whether
426 listed on the command line, obtained from --file-list, or by
427 scanning a directory. The pattern is a PCRE2 regular expres‐
428 sion, and is matched against the final component of the file
429 name, not the entire path. The -F, -w, and -x options do not
430 apply to this pattern. The option may be given any number of
431 times. If a file name matches both an --include and an --ex‐
432 clude pattern, it is excluded. There is no short form for
433 this option.
434 --include-from=filename
436 Treat each non-empty line of the file as the data for an
437 --include option. What constitutes a newline for this purpose
438 is the operating system's default. The --newline option has
439 no effect on this option. This option may be given any number
440 of times; all the files are read.
441 --include-dir=pattern
443 If any --include-dir patterns are specified, the only direc‐
444 tories that are processed are those whose names match one of
445 the patterns and do not match an --exclude-dir pattern. This
446 applies to all directories, whether listed on the command
447 line, obtained from --file-list, or by scanning a parent di‐
448 rectory. The pattern is a PCRE2 regular expression, and is
449 matched against the final component of the directory name,
450 not the entire path. The -F, -w, and -x options do not apply
451 to this pattern. The option may be given any number of times.
452 If a directory matches both --include-dir and --exclude-dir,
453 it is excluded. There is no short form for this option.
454 -L, --files-without-match
456 Instead of outputting lines from the files, just output the
457 names of the files that do not contain any lines that would
458 have been output. Each file name is output once, on a sepa‐
459 rate line by default, but if the -Z option is set, they are
460 separated by zero bytes instead of newlines. This option
461 overrides any previous -H, -h, or -l options.
462 -l, --files-with-matches
464 Instead of outputting lines from the files, just output the
465 names of the files containing lines that would have been out‐
466 put. Each file name is output once, on a separate line, but
467 if the -Z option is set, they are separated by zero bytes in‐
468 stead of newlines. Searching normally stops as soon as a
469 matching line is found in a file. However, if the -c (count)
470 option is also used, matching continues in order to obtain
471 the correct count, and those files that have at least one
472 match are listed along with their counts. Using this option
473 with -c is a way of suppressing the listing of files with no
474 matches that occurs with -c on its own. This option overrides
475 any previous -H, -h, or -L options.
476 --label=name
478 This option supplies a name to be used for the standard input
479 when file names are being output. If not supplied, "(standard
480 input)" is used. There is no short form for this option.
481 --line-buffered
483 When this option is given, non-compressed input is read and
484 processed line by line, and the output is flushed after each
485 write. By default, input is read in large chunks, unless
486 pcre2grep can determine that it is reading from a terminal,
487 which is currently possible only in Unix-like environments or
488 Windows. Output to terminal is normally automatically flushed
489 by the operating system. This option can be useful when the
490 input or output is attached to a pipe and you do not want
491 pcre2grep to buffer up large amounts of data. However, its
492 use will affect performance, and the -M (multiline) option
493 ceases to work. When input is from a compressed .gz or .bz2
494 file, --line-buffered is ignored.
495 --line-offsets
497 Instead of showing lines or parts of lines that match, show
498 each match as a line number, the offset from the start of the
499 line, and a length. The line number is terminated by a colon
500 (as usual; see the -n option), and the offset and length are
501 separated by a comma. In this mode, --colour has no effect,
502 and no context is shown. That is, the -A, -B, and -C options
503 are ignored. If there is more than one match in a line, each
504 of them is shown separately. This option is mutually exclu‐
505 sive with --output, --file-offsets, and --only-matching.
506 --locale=locale-name
508 This option specifies a locale to be used for pattern match‐
509 ing. It overrides the value in the LC_ALL or LC_CTYPE envi‐
510 ronment variables. If no locale is specified, the PCRE2 li‐
511 brary's default (usually the "C" locale) is used. There is no
512 short form for this option.
513 -M, --multiline
515 Allow patterns to match more than one line. When this option
516 is set, the PCRE2 library is called in "multiline" mode. This
517 allows a matched string to extend past the end of a line and
518 continue on one or more subsequent lines. Patterns used with
519 -M may usefully contain literal newline characters and inter‐
520 nal occurrences of ^ and $ characters. The output for a suc‐
521 cessful match may consist of more than one line. The first
522 line is the line in which the match started, and the last
523 line is the line in which the match ended. If the matched
524 string ends with a newline sequence, the output ends at the
525 end of that line. If -v is set, none of the lines in a
526 multi-line match are output. Once a match has been handled,
527 scanning restarts at the beginning of the line after the one
528 in which the match ended.
529 The newline sequence that separates multiple lines must be
531 matched as part of the pattern. For example, to find the
532 phrase "regular expression" in a file where "regular" might
533 be at the end of a line and "expression" at the start of the
534 next line, you could use this command:
535 pcre2grep -M 'regular\s+expression' <file>
537 The \s escape sequence matches any white space character, in‐
539 cluding newlines, and is followed by + so as to match trail‐
540 ing white space on the first line as well as possibly han‐
541 dling a two-character newline sequence.
542 There is a limit to the number of lines that can be matched,
544 imposed by the way that pcre2grep buffers the input file as
545 it scans it. With a sufficiently large processing buffer,
546 this should not be a problem, but the -M option does not work
547 when input is read line by line (see --line-buffered.)
548 -m number, --max-count=number
550 Stop processing after finding number matching lines, or non-
551 matching lines if -v is also set. Any trailing context lines
552 are output after the final match. In multiline mode, each
553 multiline match counts as just one line for this purpose. If
554 this limit is reached when reading the standard input from a
555 regular file, the file is left positioned just after the last
556 matching line. If -c is also set, the count that is output
557 is never greater than number. This option has no effect if
558 used with -L, -l, or -q, or when just checking for a match in
559 a binary file.
560 --match-limit=number
562 Processing some regular expression patterns may take a very
563 long time to search for all possible matching strings. Others
564 may require a very large amount of memory. There are three
565 options that set resource limits for matching.
566 The --match-limit option provides a means of limiting comput‐
568 ing resource usage when processing patterns that are not go‐
569 ing to match, but which have a very large number of possibil‐
570 ities in their search trees. The classic example is a pattern
571 that uses nested unlimited repeats. Internally, PCRE2 has a
572 counter that is incremented each time around its main pro‐
573 cessing loop. If the value set by --match-limit is reached,
574 an error occurs.
575 The --heap-limit option specifies, as a number of kibibytes
577 (units of 1024 bytes), the maximum amount of heap memory that
578 may be used for matching.
579 The --depth-limit option limits the depth of nested back‐
581 tracking points, which indirectly limits the amount of memory
582 that is used. The amount of memory needed for each backtrack‐
583 ing point depends on the number of capturing parentheses in
584 the pattern, so the amount of memory that is used before this
585 limit acts varies from pattern to pattern. This limit is of
586 use only if it is set smaller than --match-limit.
587 There are no short forms for these options. The default lim‐
589 its can be set when the PCRE2 library is compiled; if they
590 are not specified, the defaults are very large and so effec‐
591 tively unlimited.
592 --max-buffer-size=number
594 This limits the expansion of the processing buffer, whose
595 initial size can be set by --buffer-size. The maximum buffer
596 size is silently forced to be no smaller than the starting
597 buffer size.
598 -N newline-type, --newline=newline-type
600 Six different conventions for indicating the ends of lines in
601 scanned files are supported. For example:
602 pcre2grep -N CRLF 'some pattern' <file>
604 The newline type may be specified in upper, lower, or mixed
606 case. If the newline type is NUL, lines are separated by bi‐
607 nary zero characters. The other types are the single-charac‐
608 ter sequences CR (carriage return) and LF (linefeed), the
609 two-character sequence CRLF, an "anycrlf" type, which recog‐
610 nizes any of the preceding three types, and an "any" type,
611 for which any Unicode line ending sequence is assumed to end
612 a line. The Unicode sequences are the three just mentioned,
613 plus VT (vertical tab, U+000B), FF (form feed, U+000C), NEL
614 (next line, U+0085), LS (line separator, U+2028), and PS
615 (paragraph separator, U+2029).
616 When the PCRE2 library is built, a default line-ending se‐
618 quence is specified. This is normally the standard sequence
619 for the operating system. Unless otherwise specified by this
620 option, pcre2grep uses the library's default.
621 This option makes it possible to use pcre2grep to scan files
623 that have come from other environments without having to mod‐
624 ify their line endings. If the data that is being scanned
625 does not agree with the convention set by this option,
626 pcre2grep may behave in strange ways. Note that this option
627 does not apply to files specified by the -f, --exclude-from,
628 or --include-from options, which are expected to use the op‐
629 erating system's standard newline sequence.
630 -n, --line-number
632 Precede each output line by its line number in the file, fol‐
633 lowed by a colon for matching lines or a hyphen for context
634 lines. If the file name is also being output, it precedes the
635 line number. When the -M option causes a pattern to match
636 more than one line, only the first is preceded by its line
637 number. This option is forced if --line-offsets is used.
638 --no-jit If the PCRE2 library is built with support for just-in-time
640 compiling (which speeds up matching), pcre2grep automatically
641 makes use of this, unless it was explicitly disabled at build
642 time. This option can be used to disable the use of JIT at
643 run time. It is provided for testing and working round prob‐
644 lems. It should never be needed in normal use.
645 -O text, --output=text
647 When there is a match, instead of outputting the line that
648 matched, output just the text specified in this option, fol‐
649 lowed by an operating-system standard newline. In this mode,
650 --colour has no effect, and no context is shown. That is,
651 the -A, -B, and -C options are ignored. The --newline option
652 has no effect on this option, which is mutually exclusive
653 with --only-matching, --file-offsets, and --line-offsets.
654 However, like --only-matching, if there is more than one
655 match in a line, each of them causes a line of output.
656 Escape sequences starting with a dollar character may be used
658 to insert the contents of the matched part of the line and/or
659 captured substrings into the text.
660 $<digits> or ${<digits>} is replaced by the captured sub‐
662 string of the given decimal number; zero substitutes the
663 whole match. If the number is greater than the number of cap‐
664 turing substrings, or if the capture is unset, the replace‐
665 ment is empty.
666 $a is replaced by bell; $b by backspace; $e by escape; $f by
668 form feed; $n by newline; $r by carriage return; $t by tab;
669 $v by vertical tab.
670 $o<digits> or $o{<digits>} is replaced by the character whose
672 code point is the given octal number. In the first form, up
673 to three octal digits are processed. When more digits are
674 needed in Unicode mode to specify a wide character, the sec‐
675 ond form must be used.
676 $x<digits> or $x{<digits>} is replaced by the character rep‐
678 resented by the given hexadecimal number. In the first form,
679 up to two hexadecimal digits are processed. When more digits
680 are needed in Unicode mode to specify a wide character, the
681 second form must be used.
682 Any other character is substituted by itself. In particular,
684 $$ is replaced by a single dollar.
685 -o, --only-matching
687 Show only the part of the line that matched a pattern instead
688 of the whole line. In this mode, no context is shown. That
689 is, the -A, -B, and -C options are ignored. If there is more
690 than one match in a line, each of them is shown separately,
691 on a separate line of output. If -o is combined with -v (in‐
692 vert the sense of the match to find non-matching lines), no
693 output is generated, but the return code is set appropri‐
694 ately. If the matched portion of the line is empty, nothing
695 is output unless the file name or line number are being
696 printed, in which case they are shown on an otherwise empty
697 line. This option is mutually exclusive with --output,
698 --file-offsets and --line-offsets.
699 -onumber, --only-matching=number
701 Show only the part of the line that matched the capturing
702 parentheses of the given number. Up to 50 capturing parenthe‐
703 ses are supported by default. This limit can be changed via
704 the --om-capture option. A pattern may contain any number of
705 capturing parentheses, but only those whose number is within
706 the limit can be accessed by -o. An error occurs if the num‐
707 ber specified by -o is greater than the limit.
708 -o0 is the same as -o without a number. Because these options
710 can be given without an argument (see above), if an argument
711 is present, it must be given in the same shell item, for ex‐
712 ample, -o3 or --only-matching=2. The comments given for the
713 non-argument case above also apply to this option. If the
714 specified capturing parentheses do not exist in the pattern,
715 or were not set in the match, nothing is output unless the
716 file name or line number are being output.
717 If this option is given multiple times, multiple substrings
719 are output for each match, in the order the options are
720 given, and all on one line. For example, -o3 -o1 -o3 causes
721 the substrings matched by capturing parentheses 3 and 1 and
722 then 3 again to be output. By default, there is no separator
723 (but see the next but one option).
724 --om-capture=number
726 Set the number of capturing parentheses that can be accessed
727 by -o. The default is 50.
728 --om-separator=text
730 Specify a separating string for multiple occurrences of -o.
731 The default is an empty string. Separating strings are never
732 coloured.
733 -q, --quiet
735 Work quietly, that is, display nothing except error messages.
736 The exit status indicates whether or not any matches were
737 found.
738 -r, --recursive
740 If any given path is a directory, recursively scan the files
741 it contains, taking note of any --include and --exclude set‐
742 tings. By default, a directory is read as a normal file; in
743 some operating systems this gives an immediate end-of-file.
744 This option is a shorthand for setting the -d option to "re‐
745 curse".
746 --recursion-limit=number
748 This is an obsolete synonym for --depth-limit. See --match-
749 limit above for details.
750 -s, --no-messages
752 Suppress error messages about non-existent or unreadable
753 files. Such files are quietly skipped. However, the return
754 code is still 2, even if matches were found in other files.
755 -t, --total-count
757 This option is useful when scanning more than one file. If
758 used on its own, -t suppresses all output except for a grand
759 total number of matching lines (or non-matching lines if -v
760 is used) in all the files. If -t is used with -c, a grand to‐
761 tal is output except when the previous output is just one
762 line. In other words, it is not output when just one file's
763 count is listed. If file names are being output, the grand
764 total is preceded by "TOTAL:". Otherwise, it appears as just
765 another number. The -t option is ignored when used with -L
766 (list files without matches), because the grand total would
767 always be zero.
768 -u, --utf Operate in UTF-8 mode. This option is available only if PCRE2
770 has been compiled with UTF-8 support. All patterns (including
771 those for any --exclude and --include options) and all lines
772 that are scanned must be valid strings of UTF-8 characters.
773 If an invalid UTF-8 string is encountered, an error occurs.
774 -U, --utf-allow-invalid
776 As --utf, but in addition subject lines may contain invalid
777 UTF-8 code unit sequences. These can never form part of any
778 pattern match. Patterns themselves, however, must still be
779 valid UTF-8 strings. This facility allows valid UTF-8 strings
780 to be sought within arbitrary byte sequences in executable or
781 other binary files. For more details about matching in non-
782 valid UTF-8 strings, see the pcre2unicode(3) documentation.
783 -V, --version
785 Write the version numbers of pcre2grep and the PCRE2 library
786 to the standard output and then exit. Anything else on the
787 command line is ignored.
788 -v, --invert-match
790 Invert the sense of the match, so that lines which do not
791 match any of the patterns are the ones that are found. When
792 this option is set, options such as --only-matching and
793 --output, which specify parts of a match that are to be out‐
794 put, are ignored.
795 -w, --word-regex, --word-regexp
797 Force the patterns only to match "words". That is, there must
798 be a word boundary at the start and end of each matched
799 string. This is equivalent to having "\b(?:" at the start of
800 each pattern, and ")\b" at the end. This option applies only
801 to the patterns that are matched against the contents of
802 files; it does not apply to patterns specified by any of the
803 --include or --exclude options.
804 -x, --line-regex, --line-regexp
806 Force the patterns to start matching only at the beginnings
807 of lines, and in addition, require them to match entire
808 lines. In multiline mode the match may be more than one line.
809 This is equivalent to having "^(?:" at the start of each pat‐
810 tern and ")$" at the end. This option applies only to the
811 patterns that are matched against the contents of files; it
812 does not apply to patterns specified by any of the --include
813 or --exclude options.
814 -Z, --null
816 Terminate files names in the regular output with a zero byte
817 (the NUL character) instead of what would normally appear.
818 This is useful when file names contain unusual characters
819 such as colons, hyphens, or even newlines. The option does
820 not apply to file names in error messages.
821
823 The environment variables LC_ALL and LC_CTYPE are examined, in that or‐
825 der, for a locale. The first one that is set is used. This can be over‐
826 ridden by the --locale option. If no locale is set, the PCRE2 library's
827 default (usually the "C" locale) is used.
828
830 The -N (--newline) option allows pcre2grep to scan files with newline
832 conventions that differ from the default. This option affects only the
833 way scanned files are processed. It does not affect the interpretation
834 of files specified by the -f, --file-list, --exclude-from, or --in‐
835 clude-from options.
836 Any parts of the scanned input files that are written to the standard
838 output are copied with whatever newline sequences they have in the in‐
839 put. However, if the final line of a file is output, and it does not
840 end with a newline sequence, a newline sequence is added. If the new‐
841 line setting is CR, LF, CRLF or NUL, that line ending is output; for
842 the other settings (ANYCRLF or ANY) a single NL is used.
843 The newline setting does not affect the way in which pcre2grep writes
845 newlines in informational messages to the standard output and error
846 streams. Under Windows, the standard output is set to be binary, so
847 that "\r\n" at the ends of output lines that are copied from the input
848 is not converted to "\r\r\n" by the C I/O library. This means that any
849 messages written to the standard output must end with "\r\n". For all
850 other operating systems, and for all messages to the standard error
851 stream, "\n" is used.
852
854 Many of the short and long forms of pcre2grep's options are the same as
856 in the GNU grep program. Any long option of the form --xxx-regexp (GNU
857 terminology) is also available as --xxx-regex (PCRE2 terminology). How‐
858 ever, the --depth-limit, --file-list, --file-offsets, --heap-limit,
859 --include-dir, --line-offsets, --locale, --match-limit, -M, --multi‐
860 line, -N, --newline, --om-separator, --output, -u, --utf, -U, and
861 --utf-allow-invalid options are specific to pcre2grep, as is the use of
862 the --only-matching option with a capturing parentheses number.
863 Although most of the common options work the same way, a few are dif‐
865 ferent in pcre2grep. For example, the --include option's argument is a
866 glob for GNU grep, but a regular expression for pcre2grep. If both the
867 -c and -l options are given, GNU grep lists only file names, without
868 counts, but pcre2grep gives the counts as well.
869
871 There are four different ways in which an option with data can be spec‐
873 ified. If a short form option is used, the data may follow immedi‐
874 ately, or (with one exception) in the next command line item. For exam‐
875 ple:
876 -f/some/file
878 -f /some/file
879 The exception is the -o option, which may appear with or without data.
881 Because of this, if data is present, it must follow immediately in the
882 same item, for example -o3.
883 If a long form option is used, the data may appear in the same command
885 line item, separated by an equals character, or (with two exceptions)
886 it may appear in the next command line item. For example:
887 --file=/some/file
889 --file /some/file
890 Note, however, that if you want to supply a file name beginning with ~
892 as data in a shell command, and have the shell expand ~ to a home di‐
893 rectory, you must separate the file name from the option, because the
894 shell does not treat ~ specially unless it is at the start of an item.
895 The exceptions to the above are the --colour (or --color) and --only-
897 matching options, for which the data is optional. If one of these op‐
898 tions does have data, it must be given in the first form, using an
899 equals character. Otherwise pcre2grep will assume that it has no data.
900
902 pcre2grep has, by default, support for calling external programs or
904 scripts or echoing specific strings during matching by making use of
905 PCRE2's callout facility. However, this support can be completely or
906 partially disabled when pcre2grep is built. You can find out whether
907 your binary has support for callouts by running it with the --help op‐
908 tion. If callout support is completely disabled, all callouts in pat‐
909 terns are ignored by pcre2grep. If the facility is partially disabled,
910 calling external programs is not supported, and callouts that request
911 it are ignored.
912 A callout in a PCRE2 pattern is of the form (?C<arg>) where the argu‐
914 ment is either a number or a quoted string (see the pcre2callout docu‐
915 mentation for details). Numbered callouts are ignored by pcre2grep;
916 only callouts with string arguments are useful.
917 Echoing a specific string
919 Starting the callout string with a pipe character invokes an echoing
921 facility that avoids calling an external program or script. This facil‐
922 ity is always available, provided that callouts were not completely
923 disabled when pcre2grep was built. The rest of the callout string is
924 processed as a zero-terminated string, which means it should not con‐
925 tain any internal binary zeros. It is written to the output, having
926 first been passed through the same escape processing as text from the
927 --output (-O) option (see above). However, $0 cannot be used to insert
928 a matched substring because the match is still in progress. Instead,
929 the single character '0' is inserted. Any syntax errors in the string
930 (for example, a dollar not followed by another character) causes the
931 callout to be ignored. No terminator is added to the output string, so
932 if you want a newline, you must include it explicitly using the escape
933 $n. For example:
934 pcre2grep '(.)(..(.))(?C"|[$1] [$2] [$3]$n")' <some file>
936 Matching continues normally after the string is output. If you want to
938 see only the callout output but not any output from an actual match,
939 you should end the pattern with (*FAIL).
940 Calling external programs or scripts
942 This facility can be independently disabled when pcre2grep is built. It
944 is supported for Windows, where a call to _spawnvp() is used, for VMS,
945 where lib$spawn() is used, and for any Unix-like environment where
946 fork() and execv() are available.
947 If the callout string does not start with a pipe (vertical bar) charac‐
949 ter, it is parsed into a list of substrings separated by pipe charac‐
950 ters. The first substring must be an executable name, with the follow‐
951 ing substrings specifying arguments:
952 executable_name|arg1|arg2|...
954 Any substring (including the executable name) may contain escape se‐
956 quences started by a dollar character. These are the same as for the
957 --output (-O) option documented above, except that $0 cannot insert the
958 matched string because the match is still in progress. Instead, the
959 character '0' is inserted. If you need a literal dollar or pipe charac‐
960 ter in any substring, use $$ or $| respectively. Here is an example:
961 echo -e "abcde\n12345" | pcre2grep \
963 '(?x)(.)(..(.))
964 (?C"/bin/echo|Arg1: [$1] [$2] [$3]|Arg2: $|${1}$| ($4)")()' -
965 Output:
967 Arg1: [a] [bcd] [d] Arg2: |a| ()
969 abcde
970 Arg1: [1] [234] [4] Arg2: |1| ()
971 12345
972 The parameters for the system call that is used to run the program or
974 script are zero-terminated strings. This means that binary zero charac‐
975 ters in the callout argument will cause premature termination of their
976 substrings, and therefore should not be present. Any syntax errors in
977 the string (for example, a dollar not followed by another character)
978 causes the callout to be ignored. If running the program fails for any
979 reason (including the non-existence of the executable), a local match‐
980 ing failure occurs and the matcher backtracks in the normal way.
981
983 It is possible to supply a regular expression that takes a very long
985 time to fail to match certain lines. Such patterns normally involve
986 nested indefinite repeats, for example: (a+)*\d when matched against a
987 line of a's with no final digit. The PCRE2 matching function has a re‐
988 source limit that causes it to abort in these circumstances. If this
989 happens, pcre2grep outputs an error message and the line that caused
990 the problem to the standard error stream. If there are more than 20
991 such errors, pcre2grep gives up.
992 The --match-limit option of pcre2grep can be used to set the overall
994 resource limit. There are also other limits that affect the amount of
995 memory used during matching; see the discussion of --heap-limit and
996 --depth-limit above.
997
999 Exit status is 0 if any matches were found, 1 if no matches were found,
1001 and 2 for syntax errors, overlong lines, non-existent or inaccessible
1002 files (even if matches were found in other files) or too many matching
1003 errors. Using the -s option to suppress error messages about inaccessi‐
1004 ble files does not affect the return code.
1005 When run under VMS, the return code is placed in the symbol
1007 PCRE2GREP_RC because VMS does not distinguish between exit(0) and
1008 exit(1).
1009
1011 pcre2pattern(3), pcre2syntax(3), pcre2callout(3), pcre2unicode(3).
1013
1015 Philip Hazel
1017 Retired from University Computing Service
1018 Cambridge, England.
1019
1021 Last updated: 21 November 2022
1023 Copyright (c) 1997-2022 University of Cambridge.
1024PCRE2 10.41 21 November 2022 PCRE2GREP(1)